Lesson 5: Potable Water Flashcards
True or False.
For humans, it’s fine for the water we drink to have high levels of dissolved salt/ microbes.
- False.
- Drinking water should have sufficiently low levels of dissolved salts and microbes.
What is “potable water?”
- Water that is safe to drink is known as “potable water.”
Why is potable water not PURE (in the chemical sense?)
- Because, potable water contains dissolved substances.
What does the methods used to obtain potable water depend on?
2 main things!!
1.) Avaliable supplies of water.
2.) Local conditions.
What is “fresh water”?
- Fresh water: water that contains low levels of dissolved substances.
How is fresh water collected in the UK?
- Rain water provides fresh water that collects in the ground and in lakes and river.
What are the 3 steps that most potable water is produced by?
1.) Chose an appropriate source of fresh water.
2.)Passing the water through filter beds
3.) Sterilising
What 3 types of sterilising agents are there (used to produce potable water?)
1.) Chlroine
2.) ozone
3.) Ultraviolet light.
If supplies of fresh water is limited, what might some people need to do to obtain potable water?
- Desalination of salty or sea water may be required.
What are the two different methods of desalination?
1.) Distillation
2.) Processes that use membranes ie. reverse osmosis.
What is the issue with the two difference processes of desalination?
- They require large amounts of energy.
Why is it important to pass fresh water through filter beds (in the second step of producing potable water?)
- Removes large twigs/ gravel/ solid bits.
Why is it important to sterilise fresh water before you drink it?
- Kill any harmful bacteria/microbes.
Why is desalination used?
- Reduces the levels of dissolved salts down to an acceptable level.
